When it comes to global carbon emission is a tax the best form of defence? To make the European Green Deal work, the EU is considering a levy on carbon-intensive goods manufactured beyond its borders. But will a carbon border tax spawn a massive bureaucracy and lead to accusations of protectionism? To find out, Nicholas Barrett talked to Georg Zachmann and Ben McWilliams from Bruegel and Gabriel Felbermayr, President of the Kiel Institute for the World Economy